ECG's

Question 1

Rate
What is normal speed?
How do you calculate rate from ECG?

Answer 1

At usual speed 25mm/s (5 big squares)

To calculate divide 300 by the number of big squares

Question 2

Rhythm

Answer 2

Check rhythm using card technique to check R intervals are regular.
If not-
-Is there a regular lengthening and shortening (with respiration)
-Different rates that are multiples of each other
-100% irregular, AF or VF

Question 3

Axis

Answer 3

Relates to the average direction of the flow of electricity/depolarisation across the heart

Question 4

P wave

Answer 4

Upright in II, III, aVF but inverted in aVR.

Absent P wave = AF

Question 5

PR Interval

Answer 5

Measured from start of P wave to start of QRS Comples. Normal duration 0.12-0.2

Prolonged PR interval implies delayed AV conduction/ 1st degree heart block.

Question 6

QRS Complex

Answer 6

Duration less than 0.12.

Normal Q waves, <0.04 wide and <2mm deep. Deep and wide Q waves may occur within a few hours of an MI.

Question 7

QT Interval

Answer 7

From start of QRS wave to end of T wave.

Question 8

ST Segment

Answer 8

Usually isoelectric. Planar elevation or depression implies infarction or ischaemia.